Low RPM surging and vibrations

It's on my list of things to get too, I just have not gotten to it yet. But my thought on this is either the electronics are off, the throttle body blade stem or sleeve is worn. It really is the oddest thing. When I stop at a light, the RPM's will dip to 450 sometimes it will stay there and shutter sometimes it will bounce to 650. When the RPMS are up it runs great.

Michael Byam said:

So has anyone come up with a fix for this issue. 2 dealerships can’t figure it out. Been mopar my whole life. Switching to someone else soon. This is crap

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Hello MichaelByam,
We certainly understand your frustration. If you would like to be connected with a Case Specialist to add an additional layer of assistance please reach out to us privately.
Laura
RamCares

I'm not a RAM expert (only owned mine 16 months), but Hemi395 has some good advice. At > 100K miles, making sure the MAP sensor (ca. $30 US) is NOT the problem would be high on my list - it's cheap, and it will eliminate one possible cause.

I'm used to maintaining a couple of turbo engines on my daughters' two cars. Those have both MAF and MAP sensors, and as they age they can produce problems without necessarily setting CEL's. So the MAP in the RAM's is a simpler / cheaper deal.

The comment on throttle body electronics is also important to consider. TB cleaning is sometimes an answer, but the TB electronics are subjected to engine heat and vibration and can degrade over time. Throttle bodies are expensive (ca. $270 from one dealer), so before I condemned one, I would be sure to diagnose it carefully.

If someone with this issue has a cooperative dealer, they MIGHT fit a known-good TB and see how it affects the problem. I am not well versed enough yet to know how to competently diagnose the TB's on our 5.7L Hemi engines.

P.S. Bid Daddy - you have a symptom that I missed out on reading the thread first time. The bouncing idle is a classic intermittent (variable) vacuum leak symptom - maybe in your case a thorough check of vacuum lines & connections is in order.

Hello Everyone, I also have this issue on a 2014 Crew Cab 4x4 5.7 Hemi with about 160K miles. This issue has been present in my truck for months. I notice the rpm "bounce" maintaining any speed from about 35mph and up and in any gear and with or without cruise control. I've had it at the dealership twice, the first time they had the truck for two weeks before I demanded the truck back. They say that they confirmed it's not the transmission/torque converter, voltage going to the TPS, the Throttle Body, Intake Manifold Leaking. The second time they had the truck for 2 days and they decided that they want to try a new fuel pressure regulator...that part has been on order for a week now. Has anyone figured out a solution to this? I'm doubting that a faulty fuel pressure regulator would cause the rpm to behave that way. To me it seems like the engine controller is commanding the change because it behaves like an oscillation occurring in the control system affecting the output signal. You can see the change on the tachometer, hear the change with your ear, and it seems like you can barely feel the change in the speed or more likely feel the change in vibration of the exhaust. It is frustrating because there are times when the truck doesn't do this, but I notice it doing it everyday.

Question for those with this problem. How many of you are still running stock battery?

I have recently changed the battery. The new battery made no difference to the rpm "bounce".

Has anyone come up with a solution to this?
This has been ongoing for me for months now. the same "shudder" at low rpms/speed. Also a very rhythmic subtle surging when under light load, even at highway speeds as long as light on the accelerator. No codes present at all.

So far I have replaced all spark plugs, all new injectors, brand new fuel pump (as this was the dealerships best guess), new IAT sensor, new non factory exhaust manifolds.

I have had it to the dealership 3 times now and have had reflashes done with no change. Have had it on the super expensive scan tools and everything is reading as fine. I am at a loss and on the verge of buying a new Chev to fix the problem. I would really like to keep my truck so if anyone has come up with a fix please post it.

I kinda skimmed the thread but if electrical is suspect for your vibrations have you looked at your grounds? Some pine needles lodged between the frame and the strap, corrosion build up or anything else that could possibly interrupt making a secure ground could play havoc.

A buddy recently went and bought a new battery and while replacing it, knocked loose the ground on the frame to bat term. All he had was a pair of pliers to tighten it. He felt it was pretty snug but his car would die randomly. After finally getting it torqued properly with a socket, the issue disappeared.

Grounds. Are. Finicky. Basterds.

I am having the same issues as OP my self I've been watching my data log and I've noticed when driving at the constant speed the base spark drops about 20° but once you give it a bit of throttle it corrects its self I might have a different issue but OP's sysmtoms match mine to a T and the at idle rpm fluctuation if you flip you ac on and off it will fix the idle see if yours does the same

Wow thats crazy I am experiencing similar issues with my mine also When I’m driving and coasting when I give it light gas around 1500 rpms it shakes and you hear a funny noise not smooth at all like a hesitation but then I give it a little more gas lets say 2000 rps its goes away and smooth again you feel the power. Other than that truck runs great. Sometimes at idle you feel a slight very slight shake nothing crazy. No check engine lights or anything. Recently changed all plugs and coil packs kind of upset now i spend all this money on coils and hard labor for the same outcome. Anyone can help chime in much appreciated

Actually just came across this fix has anyone try replacing the egr valve ? Im seeing this is a common problem

Lol ... I was talking to a customer who's neighbor has a 1500 that was doing something like this, they took it in and same day they told him "adaptive transmission" is doing it's job ... I didn't doubt it , something to think about and pay some attention to ?

CAG CheechDogg said:

Lol ... I was talking to a customer who's neighbor has a 1500 that was doing something like this, they took it in and same day they told him "adaptive transmission" is doing it's job ... I didn't doubt it , something to think about and pay some attention to ?

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So your saying that it’s basically nothing wrong with anything and its just the transmission doing that because its use to getting the pedal hit slightly harder ? Also what about me being stopped at the light and that slight shake I’m having ?

ExqusiteRam said:

So your saying that it’s basically nothing wrong with anything and its just the transmission doing that because its use to getting the pedal hit slightly harder ? Also what about me being stopped at the light and that slight shake I’m having ?

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No not me lol ... but that is what they told him, this fawken CPU must have a good "AI" if it catches every little thing that we might do though right ? ..... imagine if the truck all of the sudden just took complete control and we didn't have to do anything to drive lol ....

Michael Byam said:

Zero modifications to this truck.

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Thats your problem right there...

DILLIGAF said:

Thats your problem right there...

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Not replacing those cheap parts and upgrading them right ? lol ....

Im wondering if i can have a bad egr valve and it not triggering any cels

ExqusiteRam said:

Im wondering if i can have a bad egr valve and it not triggering any cels

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Anything is possible ... less than $200 for a new one, I would just replace that anyways with how old your truck is, 2007 right ? replace the egr valve and see what it does ... if it doesn't change anything send it back and say it wasn't working right or simply enjoy the fact you just upgraded that part now lol ...

Lol true thats definitely right not expensive at all I guess I’ll give that a shot.

ExqusiteRam said:

Wow thats crazy I am experiencing similar issues with my mine also When I’m driving and coasting when I give it light gas around 1500 rpms it shakes and you hear a funny noise not smooth at all like a hesitation but then I give it a little more gas lets say 2000 rps its goes away and smooth again you feel the power. Other than that truck runs great. Sometimes at idle you feel a slight very slight shake nothing crazy. No check engine lights or anything. Recently changed all plugs and coil packs kind of upset now i spend all this money on coils and hard labor for the same outcome. Anyone can help chime in much appreciated

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I did read on another forum that an older muffler can get like this with time, similar to drone and creates vibrations from the muffler or the catalytic converters going bad too, the honeycomb inside starts to break down and feels like a vibration ... something to take a look at